Media captionHow to get by in Venezuela, when money is in short supply

It warned Mr Maduro not to threaten the safety of the Venezuelan people and said tougher sanctions could be imposed.

Mr Trump told journalists he was not considering military action but added that “all options are on the table”.

He called on other nations to follow suit in supporting Mr Guaidó.

How did nations react to the call?

Seven South American nations, Brazil, Colombia, Chile, Peru, Ecuador, Argentina and Paraguay have recognised Mr Guaidó as the legitimate president.

Canada is also supporting him, while the EU called for new elections.

The Organization of American States (OAS) also recognised Mr Guaidó as president. Venezuela withdrew from organisation in 2017, accusing it of meddling in its internal affairs.

Mexico, Bolivia and Cuba have expressed support for Mr Maduro.

What was President Maduro’s response?

He accused Washington of trying to govern Venezuela from afar and said the opposition was seeking to stage a coup.

“We’ve had enough interventionism, here we have dignity, damn it!” he said in a televised address from the presidential palace, the Miraflores, where thousands had gathered to show their support for him.

“The nation’s soldiers don’t accept a president imposed by obscure interests, nor one self-proclaimed outside of the law,” he tweeted.

Mr Maduro and his core supporters believe Venezuela’s problems are caused by US sanctions that have hampered the government by making it hard to restructure its debt.

The annual inflation rate reached 1,300,000% in the 12 months to November 2018, according to a study by the National Assembly.

Mr Maduro took office in 2013 after the death of Hugo Chavez. He was sworn in for a second term earlier this month after a vote last May that was marred by an opposition boycott and widespread claims of vote-rigging.

What happens next?

By Jonathan Marcus, BBC diplomatic correspondent

Does the Trump administration have a coherent plan for raising the pressure on the Maduro regime – such as freezing assets? Crisis could simply lead to a greater calamity for the Venezuelan people.

Much will depend on which way the Venezuelan military jumps.

For now, its generals may be backing the current regime. But will the lower ranks remain loyal to Mr Maduro or will they heed the growing unrest inside the country and the chorus of powerful voices coming from abroad?

Who is Juan Guaidó?

Image copyrightGetty Images

Mr Guaidó was a relatively unknown figure until he became president of the opposition-controlled parliament this month. Upon taking up the role, he said he had a constitutional right to assume the presidency until fresh elections were held.

The opposition won parliamentary elections in 2015, but in 2017 Mr Maduro set up a separate body, the constituent assembly, which has taken over legislative powers.

Leopoldo Lopez, Venezuela’s most popular opposition leader, is seen as the architect behind Mr Guaidó’s rise. Mr Lopez is under house arrest and considered by his supporters to be a political prisoner.

As a student, Mr Guaidó led protests against Hugo Chávez, who handpicked Mr Maduro as his successor.